The research proposed herein centers around continued surveillance for Echinococcus granulosus in Utah, and on investigations of the ecological factors which may contribute to the demonstrated high prevalence of hydatid disease in this area. Field clinics will be held periodically for examination of sheep dogs for adult E. granulosus tapeworms, and all sheep over 1 year of age killed at 4 abattoirs in central Utah will be examined for hydatid cysts. Through cooperative effort with wild-life agencies in the state, examinations will also be made on deer and coyotes in order to investigate the possibility of a sylvatic reservoir cycle in this area. In conjunction with personnel from the State Department of Health, additional clinics will be held for diagnosis of asymptomatic hydatid disease in central Utah, as well as at the Navajo Indian Reservation in southeastern Utah. Laboratory studies will be conducted to determine if different invertebrates can serve as transport hosts for the infective eggs, and to determine the effects of temperature, irradiations, relative humidity, and soil moisture extremes on survival and actual infectivity on the infective stages. Meteorologic measurements will be continued from irrigated and non-irrigated pasture plots in order to monitor those micro-environments in vegetation inhabitated by the free-living stages of many micro-organisms including the eggs of Echinococcus. An attempt will also be made to establish a successful secondary echinococcosis system whereby protoscolices can be harvested from infected gerbils when needed. In spite of the obvious time limitations, an attempt will be made to implement a feasible control program for hydatid disease in central Utah. This will involve area-wide registration and treatment of all dogs in Sanpete County, as well as an intensive effort to educate and solicit the assistance of the general public with this program.